The overall goal of our studies is to define the structural basis by which 2 families of salivary molecules might participate in (a) the formation of a protective acquired enamel pellicle and (b) the transition from pellicle formation to streptococcal colonization. These families include mucins (MG1 = high molecular weight mucin and MG2 = low molecular weight mucin) and cysteine-containing phosphoproteins (CCP's: C1a,b,c; and C3a, b, c). More precisely, these studies propose to determine the role of MG1, MG2, and CCP's in in vitro enamel pellicle formation, lubrication and streptococcal interactions. We also propose to develop site specific reagents (monoclonal antibodies) to quantitate these mucins and CCP's in normal saliva and their structural domains in vivo enamel pellicle and then utilize these reagents to define the role of mucins and CCP's in in vivo enamel pellicle formation. We will isolate and chemically characterize two known adhesins of oral streptococci, namely, LTA and the sialic acid binding protein (SA-BP) and subsequently define the structural domains of each which are responsible for their interaction with saliva. Site-specific reagents will be prepared against these structural domains to define the parameters by which these adhesins might regulate the transition from salivary mediated pellicle formation to microbial colonization (structural modulation).